First, during the Battle of Leipzig (AKA the Battle of Nations), he was defeated by the GIANT coalition of Russia, Prussia, Austria, Sweden, the United Kingdom, Spain, Portugal, Sicily, and Sardinia. It was 430,000 vs only about 200,000. He fled back to Paris, and they chased him.

Second, during the Battle of Waterloo, just as Napoleon was about to win, Gebhard von Blucher came in and reinforced the Duke of Wellington, allowing him to win.

I call those two losses unfair.